1. Field of the Invention
This invention concerns technology for correcting images to be transferred to paper.
2. Description of the Related Art
In an image forming apparatus that allows transferring/fixing of paper formed by electronic photography systems, images that have been formed on a photoreceptor medium are corrected, transferred and fixed to appropriate locations on a paper that is the recording medium being used (see, for example, Japanese Patent Application Laid-Open Publication No. 2000-259044, hereinafter, JP 2000-259044).
The image forming apparatus disclosed in JP 2000-259044 is capable of correcting an image that will be transferred/fixed based on the state of the paper, and of transferring and fixing the image in an appropriate location of the paper, thereby enabling formation of the image with high precision on the paper.
When performing image formation, the unused paper has moisture which evaporates because of the heat and added pressure when the image is being fixed, giving rise to lengthening. As well, for an inkjet-based image forming apparatus, swelling of paper occurs because of absorption of ink in the spaces between the fibers of the paper (capillarity) when the ink is absorbed into the paper, and it has been reported that this gives rise to lengthening of the paper, in the same way as occurs in paper after fixing. For this reason, when forming an image, correction of the image and forming of the image taking into account this lengthening, is performed. On the other hand, for paper that has become used by having images formed on only one side, because it has already been lengthened once, it is desirable to correct the images by taking into account this lengthening. In JP 2000-259044, there is disclosed a technique for correcting an image and recording on the paper the corrected image; but it does not disclose a design that performs correction of images on the reverse side by taking into account paper that has already been lengthened. For this reason, using the image forming apparatus disclosed in JP 2000-259044, it is impossible to form a highly precise image on a reverse side of a paper.
As well, there is a long grain and a short grain in the paper, depending on the direction of the fibers. For an image forming apparatus, because the amount of lengthening of the paper differs depending on a direction of the paper grain when the paper passes through a fixing roller that performs a fixing process, it is desirable to perform a correction taking into account this lengthening at the time of recording the image on the paper.
However, with the image forming apparatus disclosed in JP 2000-259044, there is no disclosure of a design for performing correction of images taking paper grain into account. For this reason, with the image forming apparatus disclosed in JP 2000-259044, it is impossible to form images with good precision that take paper grain into account.